This has somewhat subtle implications. For a concrete example, this
changes the `-trimpath` behavior from only affecting the named pkg to
affecting all pkgs, which broke ginkgo, which seems to try to strip its
own `pwd` prefix. But since that runs in run-in-gopath, and not in
KUBE_ROOT, it fails to strip anything.
e.g.
before this, strings in the binary would be like
/home/user/kube/_output/local/go/src/k8s.io/kubernetes/vendor/github.com/onsi/ginkgo/...
Ginkgo would find its own root as
/home/user/kube/_output/local/go/src/k8s.io/kubernetes/
so it would produce
vendor/github.com/onsi/ginkgo/...
in logs.
after this, strings in the binary strip the KUBE_ROOT and be like:
_output/local/go/src/k8s.io/kubernetes/vendor/github.com/onsi/ginkgo/...
Ginkgo would find its own root as
/home/user/kube/_output/local/go/src/k8s.io/kubernetes/
so it would not strip anything, and produce
_output/local/go/src/k8s.io/kubernetes/vendor/github.com/onsi/ginkgo/...
in logs.
bf27cad256